The invention relates to a lift-augmenting flap, in particular a leading edge flap, for an aerodynamically effective wing.
From the state of the art a large number of high-lift components are known which are designed to improve the lift characteristics of an aerodynamically effective wing, which high-lift components are used to increase the curvature and/or extent of the wing profile in wing depth direction and thus to increase the lift of the wing.
High-lift components of this type, which components in relation to the flow direction are provided at the front of the wing profile, are basically divided into leading edge flaps, which essentially without interruption follow on at the front of the wing profile, and leading edge slats, where there is a gap between the rear edge of the leading edge slat and the front of the actual wing, through which gap energy-rich air is led from the underside of the leading edge slat to the top of the actual wing.
Due to a delay in the boundary layer separation the leading edge slat configuration may be advantageous during the approach to landing, however, due to increased resistance may be less advantageous for takeoff, and due to unavoidable creation of oscillation and turbulence of the air flowing through the gap region said leading edge slat configuration may represent a significant source of noise.
Furthermore, a number of leading edge flaps may be known that comprise a flexible shell with variable curvature, wherein the rotary axis is also provided in the wing profile. Leading edge flaps are for example described in U.S. Pat. No. 4,475,702, U.S. Pat. No. 6,015,115, U.S. Pat. No. 6,796,534, U.S. Pat. No. 4,200,253, U.S. Pat. No. 4,553,722 and EP 0 302 143. Such leading edge flaps with variable curvature are associated with a disadvantage not only as a result of their great design complexity but also as a result of the difficulty of maintaining the predetermined wing profile at the desired accuracy. Further leading edge flaps with variable curvature are known from U.S. Pat. No. 4,650,140 and U.S. Pat. No. 4,706,913.
U.S. Pat. No. 5,927,656 describes a leading edge flap with a rigid profile, which leading edge flap by means of a lever mechanism can be adjusted in relation to a front wing end cover of a carrying wing, wherein between the flap and the front wing end cover a gap remains that allows air to flow over from the underside of the wing profile to its top.
From EP 100 775 a leading edge flap with a rotary axis situated underneath the wing profile is known, in which leading edge flap at the top of the wing long flexible shells are provided that are not closed off on the underside of the wing.
Finally, from U.S. Pat. No. 5,544,847 and U.S. Pat. No. 5,839,699 a high-lift device is known in which a leading edge slat can be extended in relation to the wing structure, by a guide rail that is curved in a circular manner, on a virtual rotary axis situated underneath the wing profile, i.e. on the pressure side. In the extended state there is a gap between the leading edge slat and the wing structure, which gap allows air that is rich in energy to flow over from the underside of the wing to its top. On the rear of the leading edge slat strong vortex regions are created that give rise to noise emission and increased resistance.